The present invention relates to a power supply apparatus that reduces its own current consumption at the time of a light load to thereby eliminate power wastage, to thereby improve an overall power conversion efficiency thereof.
Conventionally, for example, charge pump DC/DC converters and switching regulators are known as power supply apparatuses.
A charge pump DC/DC converter uses charge and discharge of a capacitor to convert an input voltage to a predetermined output voltage.
A switching regulator switches an input voltage and converts the input voltage to a predetermined output voltage.
However, since a charge pump DC/DC converter is designed taking in account of the maximum load for its operation, its own current consumption is the same even when a load condition changes. Therefore, it does not waste the power at the time of a heavy load, but it is inconvenient that its capacity becomes excessive at the time of a light load such that the power is wasted, and the overall power conversion efficiency is lowered.
On the other hand, a switching regulator has a large current consumption but a high power convention efficiency. Accordingly, its high power conversion efficiency is effective at the time of a heavy load. However, it is inconvenient that the overall power conversion efficiency is lowered because its own current consumption is large at the time of a light load.